1. Field of the Invention
This invention relates to apparatus for cutting large diameter pipe while positioned inside the pipe.
2. Description of the Prior Art
There are various prior art devices that can cut large diameter pipe while positioned within the inside of the pipe. One such apparatus is disclosed in my U.S. Pat. No. 4,667,936. In operation of my prior apparatus, there were problems in making various adjustments, such as adjusting the angle of the cut, adjusting the position of the torches relative to the interior of the pipe, and positioning the apparatus in the center of the pipe.
Principal objects of the present invention include providing pipe cutting apparatus that is easier to operate and more accurate than the prior art. The subject apparatus has a strong frame which may be readily positioned in the interior of the pipe and has adjustment means to center the apparatus in the pipe, even if large diameter pipe is out of round.
The apparatus may be adjusted to cut any angle, and this adjustment is very precise since the elevation of the drive shaft is adjusted at the rear of the machine which is several feet from the point of cut.
A plasma arc torch replaces the acetylene, oxygen torches of my prior patent.
The gap between the plasma torch and the interior surface of the pipe can be remotely controlled to compensate for large diameter pipe being slightly out of round, and to enable continuous adjustment of the angle when making an elliptical cut.
Other objects, features, and advantages of the invention will become more apparent from the following description.